Fill in the gap in this digital chain

Look at BlueOS, Roon and Volumio.

Personally, I use a Roon server(core) in a closet, and a Raspberry Pi 4 as the Roon streamer. I'm really happy with it so far.

See here for the purchase list for the streamer (~ $150):

https://inatinear.blogspot.com/2019/12/ubuntu-and-logitech-media-server-on.html

To stream Tidal, Qobuz or Amazon Music you need a streamer. A simple, easy to use one is the Bluesound Node 2i for $500. It would connect to your wifi modem wirelessly or by wire if you want a stronger connection (ethernet cable - Cat 6, etc.).

You would connect the coax out on the Node 2i to your Denafrips DAC with a coaxial digital cable (there’s an input on your DAC labeled: Digital In, Co 1). You can get a digital cable with an RCA plug on both ends. I believe you should use a digital cable with a 75 ohm impedance for this. They are common. Audio Advisor would have them.

Then you download the BluOs app from the Apple Store or Google Play depending on whether you have an Apple or Android phone. The app is free.

Setup instructions come with the Bluesound Node 2i and once you set it up it’s really easy to use.

You want a permanent option? With digital? You do know the half-life of digital is about a year, right? When it comes to digital, the only permanent option is analog.